John Browett, the head of Apple's store operations, is leaving after just six months on the job. Scott Forstall, who's been at the company since 1997 and is seen as one of OS X's original architects, will leave next year. In the interim, he will serve as an adviser to CEO Tim Cook.

No reason was given for either departure, but both men had overseen steps that were widely criticized.

"Browett cut staffing hours at Apple's retail stores, a move the company reversed and acknowledged as a mistake. Forstall's division launched a software update in September that replaced Google Maps with Apple's first mapping application. It quickly drew unfavorable comparisons to the software it was replacing, and Apple apologized."

Jony Ive, Apple's chief designer, will take over human interface responsibilities – which governs how customers interact with Apple products. Craig Federighi will take over iOS – in addition to his responsibility of the Mac OS. Eddy Cue will take over operations for Maps and Siri; he currently runs iTunes.

"While tensions between Mr. Forstall and other executives had been mounting for some time, a recent incident appeared to play a major role in his dismissal. After an outcry among iPhone customers about bugs in the company's new mobile maps service, Mr. Forstall refused to sign a public apology over the matter, dismissing the problems as exaggerated, according to people with knowledge of the situation who declined to be named discussing confidential matters."